One month after Boris followed through his manifesto nudge and wink to West London voters (see page four) that he'd liberate them from Ken Livingstone's enlargement of the congestion charging zone - a move Candidate Johnson more or less likened to a Stalinist annexation - it's not yet clear what the full effect will be. The Campaign for Clean Air in London has drawn our attention to ominous readings from the monitoring station in Knightsbridge, but Transport for London says it's too early to do a post-WEZ traffic analysis.

Back in the autumn Peter Hendy said he was optimistic that congestion wouldn't get much worse, mentioning that with building work completed on One Hyde Park - the Candy Brothers' monument to global mammon - the single biggest generator of snarl-ups in the area had gone away. Thomasthetaxi has tweeted that he's found roads around the fringes of the ex-WEZ have become clearer.

No doubt an official assessment of the impact of abolition will emerge in time, and the quarrelling about it will last all the way up to election day. Ken, of course, has promised to restore the WEZ. But will any mayoral candidate produce a policy that truly takes on board the stark judgment about road congestion through the capital as a whole - not just the centre - of motoring researchers the RAC Foundation when responding to the draft of the Mayor's Transport Strategy last January:

[It] appears to deal with much of the rail congestion problem yet seems resigned to increasing road congestion. This does not make up a balanced approach, nor does it address the needs of most of the population and most of the businesses in London. Whilst the Strategy analyses rail and Underground congestion on a section by section basis, it looks at the congestion of roads in only very general terms - and roads carry by far the greatest share of travel demand (57%).... Initiatives such as cycling and walking are welcome, but they will not solve the problems, and risk diverting attention from issues of more importance to most Londoners and to the London economy as a whole.

Then it says:

Despite proposed improvements in public transport capacity, the Draft MTS foresees crowding continuing, particularly with likely future funding constraints. Given their apparently high tolerance of traffic congestion and delay, for drivers there will not be significantly greater incentive than today to leave their cars at home and cycle or take the bus. The Draft MTS acknowledges the expectation of growth in vehicular freight movements and car use, with car remaining the dominant mode choice in Outer London. We doubt that the Mayor's aspirations for congestion and emissions to reduce and journey times to become more reliable are achievable.

Moreover:

Increased demand for freight movement and servicing, and for trip-making in general by all modes arising from an increase in population and employment, when super-imposed on the capital's saturated road network, seriously threatens its operational viability and resilience. The goals and objectives of the Draft MTS with regard to network efficiency and environment simply are not credible without introducing effective mechanisms to control future demand for use of London's scarce road space.

That means more road pricing in the RAC Foundation's view, introduced in more sophisticated, differential, forms. The takings would be used to improve highway capacity in the capital and enhance both the public realm and public transport alternatives to the car. As things stand, the MTS anticipates road congestion rising by 14 percent over the next twenty years (page 277). It's not an appetising thought. Yet with motorists' tolerance of congestion seemingly resolutely high, selling a radical increase in road-pricing to London's voters would require a combination of very robust number crunching and great political flair. Any volunteers?